Boosting MnO2-specific capacitance via surfactant-assisted synthesis and employing redox-active electrolyte

Herein, we report a facile surfactant-assisted hydrothermal synthesis of layered MnO2 for supercapacitor applications. The effect of surfactants (sodium dodecylsulfonate, hexadecyltrimethylammonium bromide, and t-octylphenoxypolyethoxyethanol) on the morphology, porosity, and electrochemical performance of MnO2 has been established. Compared to anionic and cationic surfactants, the non-ionic surfactant prevented agglomeration of nanoparticles during synthesis because of the steric hindrance, which produced a more developed surface of MnO2 particles that facilitated ion transport. Moreover, combining the porous structure of the MnO2 electrode with the redox-active K3Fe(CN)6–Na2SO4 electrolyte significantly improved the specific capacitance up to 470 F·g−1 at 0.5 A·g−1. The Coulombic efficiency of 99.9